High glucose activates nuclear factor of activated T cells in native vascular smooth muscle

Abstract

Objective - Hyperglycemia has been suggested to play a role in the development of vascular disease associated with diabetes. Atypical Ca 2+ signaling and gene expression are characteristic of vascular dysfunction; however, little is known regarding the effects of high glucose on Ca2+-dependent transcription in the vascular wall. Methods and Results - Using confocal immunofluorescence, we show that modest elevation of extracellular glucose (ie, from 2 to 11.5 mmol/L) increased [Ca 2+]i, leading to nuclear accumulation of nuclear factor of activated T cells (NFAT) in intact cerebral arteries from mouse. This was accompanied by increased NFAT-dependent transcriptional activity. Both the increase in Ca2+ and NFAT activation were prevented by the ectonucleotidase apyrase, suggesting a mechanism involving the release of extracellular nucleotides. We provide evidence that the potent vasoconstrictors and growth stimulators UTP and UDP mediate glucose-induced NFAT activation via P2Y receptors. NFAT nuclear accumulation was inhibited by the voltage-dependent Ca2+ channel blockers verapamil and nifedipine, the calcineurin inhibitor cyclosporine A, and the novel NFAT blocker A-285222. High glucose also regulated glycogen synthase kinase 3β and c-Jun N-terminal kinase activity, yielding decreased kinase activity and reduced export of NFAT from the nucleus, providing additional mechanisms underlying the glucose-induced NFAT activation. Conclusions - Our results identify the calcineurin/NFAT signaling pathway as a potential metabolic sensor for the arterial smooth muscle response to high glucose. © 2006 American Heart Association, Inc.